Barack Obama admits problems plaguing the Obamacare website three weeks after
its launch

President Barack Obama said today "nobody is madder than me" as he admitted to the problems plaguing the website at the heart of his plan to bring health coverage to millions of Americans.

Three weeks after the launch of Healthcare.gov, the portal intended to connect the uninsured with affordable healthcare, the site's technical faults remain a major embarrassment to the White House.

"There's no sugarcoating it. The website has been too slow. People have been getting stuck during the application process," Mr Obama said. "Nobody's madder than me about the fact that the website isn't working as well as it should, which means it's going to get fixed."

While he admitted what he called "kinks in the system", Mr Obama defended his signature healthcare law and insisted it would "lift from the American people the crushing burden of unaffordable health care".

He also struck back at Republicans who have focused on the chaotic roll out of the Affordable Care Act, also known as Obamacare.

"I recognise that the Republican Party has made blocking the Affordable Care Act its signature policy idea," he said. "Sometimes it seems to be the one thing that unifies the party theses days.

Mr Obama was eager to tout the achievements of the law since its major elements went into effect on October 1, saying the number of uninsured people in Oregon had been cut by 10 per cent in three weeks.

However, his administration continues to withhold much of the data needed to judge its success.

The White House said 476,000 people had completed the first stage of applying for insurance but has so far refused to say how many have successfully reached the point where they can begin buying coverage.

Republicans have focused their attacks on Kathleen Sebelius, the health and human services secretary whose department is responsible for the law.

Mrs Sebelius turned down a request to appear before a Congressional committee this week to explain the problems with the website, leading to some conservatives to call for her resignation.

"Her refusal to testify and be transparent about it is, I think. undermining her credibility," said Marco Rubio, a Republican senator, adding "there may come a point" where he would demand for her to step down.

As pressure mounted a spokeswoman for Mrs Sebelius said she was prepared to appear before Congress "as early as next week".

The White House also refused to explicitly rule out the possibility that it could delay the January 1 implementation of the individual mandate - the tax penalty imposed on those who can afford healthcare but don't sign up - because of the website's problems.

Mr Obama said the administration was in the midst of a "tech surge", bringing in digital experts from inside and outside government to try to fix the website's problems.

Contractors involved in the repair mission told the New York Times it could be weeks before the website is fully running, with potentially millions of lines of code to adjusted.

In the meantime, the White House is pushing people towards applying by phone. The website's front page now prominently features the 24-hour application phone line and Mr Obama read the number out twice during his appearance in the Rose Garden.

Some callers have received an error message when calling the phone line but a Telegraph reporter was able to get through on Monday morning.

The president's defence of his healthcare law took 25 minutes and at the end of his speech a woman standing behind him appeared to become faint and needed to be helped away. "This happens when I talk too long," Mr Obama said to laughter.

The website is the main portal for Americans in 36 states to apply for health insurance. Another 14 states, and the Washington DC, have set up their own healthcare market places and accompanying websites.